The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor(s), to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A computing system typically has a hard disk drive (HDD) and a solid state drive (SSD) that operates as a cache. A cache controller transfers data between the HDD and the SSD. The SSD caches contents of the HDD to safeguard the HDD contents in the event of power loss.
The SSD is typically a single level cell (SLC) type memory, a type of flash memory that stores a bit of data in a cell. However, SLCs may be cost prohibitive for use in cache. To offset the cost of SLCs, external or removable memory cards such as multi-level cells (MLCs) may be employed. MLCs are a flash memory capable of storing more than a single bit of information in a cell. However, MLCs have a short life and are prone to early failure due to continuous writing. The cached contents of the removable memory are lost when the removable memory fails.